Ameliorative effects of phytochemical ingestion on viral infection in honey bees

Honey bee viruses, capable of causing a wide variety of detrimental effects, are an important dimension of honey bee health management. To date, there are no effective treatments for viral infection in honey bees and management relies largely on controlling Varroa mites, a honey bee pest capable of vectoring viruses. Plant-derived chemicals (phytochemicals) represent a broad range of substances that honey bees frequently encounter and consume, many of which are known to improve honey bee health, although their effect on bee viruses is largely unknown. This thesis project tested the therapeutic effectiveness of various phytochemicals on viral infection by measuring their ability to improve survivorship in honey bees inoculated with Israeli acute paralysis virus (IAPV). In the absence of a viable cell line, virus particles were generated, purified, and extracted from honey bee pupae by pairing established protocols with “larval crawl-outs” a novel method of pupal extraction that greatly improved the efficiency of particle production. In the first part of this project, I screened for phytochemical effects by first inoculating honey bees with viral particles and then feeding them thymol, carvacrol, p-coumaric acid, quercetin, or caffeine in a series of high-throughput bioassays, all of which were chosen based on their immune-boosting properties in honey bees. Among these candidates, caffeine was the only phytochemical capable of significantly improving survivorship and was therefore selected for additional testing. Initial screening showed that naturally-occurring concentrations of caffeine (25 ppm) were sufficient to produce an ameliorative effect on IAPV infection. Consequently, the second half of this project focused on determining the scope of caffeine effectiveness in bees inoculated and uninoculated with IAPV by performing the same type of high-throughput bioassay across a wider range of caffeine concentrations. My results indicated that caffeine may provide benefits that scale with concentration, to a point, and may partially compensate for seasonal nutritional deficits within a colony. However, the exact mechanism by which caffeine ingestion improves survivorship remains uncertain, as a comparison of viral titers between inoculated and uninoculated caffeine-fed bees revealed no significant difference between infection groupings. My findings indicate that caffeine has potential to act as an accessible and inexpensive method of treating viral infections, while also serving as a tool to further understanding of honey bee-virus interactions at a physiological and molecular level.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Hsieh, Edward M

Contributors dc:contributor

• Dolezal, Adam G
• Berenbaum, May
• Alleyne, Marianne

• honey bee
• caffeine
• phytochemical
• virus
• IAPV

Statement dc:rights

• Copyright 2020 Edward Hsieh

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/108036

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/108036